• Veterinary View Box
  • Posts
  • Elbow Masses in Older Cats? New Study Unravels Synovial Cyst–Myxoma Link

Elbow Masses in Older Cats? New Study Unravels Synovial Cyst–Myxoma Link

Veterinary Pathology 2020

Linden E. Craig, Paula M. Krimer, Alicia D. O’Toole

Background:
Synovial cysts and myxomatous lesions in synovial joints are rarely documented in cats, despite the prevalence of degenerative joint disease (DJD). The study aimed to characterize the clinical, histological, and prognostic features of such lesions in cats, hypothesizing a potential continuum from synovial cysts to synovial myxomas and a possible link to underlying DJD.

Methods:
A retrospective review was conducted using pathology databases from two veterinary institutions spanning 2002 to 2018. Sixteen feline cases with synovial cysts and/or myxomas were identified. Histologic confirmation and immunohistochemistry (IHC) were performed. Lesions were categorized based on morphology (cystic, myxomatous, or both). Data on clinical presentation, treatment, and outcomes were compiled from medical records.

Results:
Most lesions were unilateral and localized to the elbow (12/16), in contrast to the bilateral nature of DJD seen in many cases. The average age of affected cats was 13.4 years. Lesions included synovial cysts (3 cases), myxomas (2), or combined features (11). Cysts were lined by synoviocyte-like cells; myxomas were solid, myxoid proliferations of stellate cells. IHC confirmed mesenchymal origin (vimentin+) and the presence of macrophages (IBA-1+, CD18+). Lesions grew slowly and were non-lethal; most cats lived with the condition for years without severe clinical consequences.

Limitations:
The study was retrospective and limited by incomplete records for some cases, including sparse data on clinical progression and treatment outcomes. Sampling bias may have affected lesion representation, especially in biopsies lacking both cystic and myxomatous components.

Conclusions:
Synovial cysts and myxomas in older cats, especially those with DJD, may represent a disease continuum. These lesions are typically benign, slow-growing, and non-metastatic, with elbow joints being most frequently involved. Awareness of this condition is important for accurate diagnosis and management, although prognosis remains favorable.

Synovial cysts and myxomas, cat. Figure 1. Case 1, right elbow. Typical gross appearance. Figure 2. Case 2, elbow. Synovial lesion composed of cystic and solid areas. Hematoxylin and eosin (HE). Figure 3. Case 14, antebrachium. Alternating cystic and solid areas. HE. Figure 4. Case 4, elbow. Foamy macrophages within myxomatous stroma. HE.

How did we do?

Login or Subscribe to participate in polls.

Disclaimer: The summary generated in this email was created by an AI large language model. Therefore errors may occur. Reading the article is the best way to understand the scholarly work. The figure presented here remains the property of the publisher or author and subject to the applicable copyright agreement. It is reproduced here as an educational work. If you have any questions or concerns about the work presented here, reply to this email.